Hydraulic jack



July 18, 1944. V w. E. MAlNwARxNG 2,354,036

HYDRAULIC JACK Filed OCL. 3l, 1942 Inventor: Walter` E. Manwav'mg,

by Maw/6. MM

-is Attorney.

Patented July 18, 1944 HYDRAULIC` JACK Walter E. Mainwaring, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application October 31, 1942 Serial No. 464,128

4 Claims. (Cl. 254-93) The present invention relates to hydraulic jack and brake arrangements for vertical generators and the like. Upon shutdown of vertical electric generators, such as are used for example in hydro-electric power stations, it is often desirable to bring the generator quickly from full speed to standstill and also to relieve the pressure of the generator weight on the thrust bearing whilethe generator is out of operation.` This has been accomplished heretofore by the provision of brake means to slow down the generator and jack supporting means for relieving the pressure on thrust bearings during standstill.

One object of my invention is toprovide an improved construction of hydraulick jack and brake arrangements for vertical generators and the like which is both rugged in construction and requires comparatively little space.

Another object of my invention is to provide an improved construction of hydraulic jack arrangements.

For a consideration of what I believe to be novel and my invention, attention isdirected to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 illustrates a sectional View of a hydraulic jack arrangement embodying my invention; Figs. 2 and 3 show front views of the arrangement of Fig. 1 in two diierent operating positions; and Fig. 4 shows a vertical generator arrangement according to my invention.

A hydraulic jack and brake arrangement for vertical electric generators and the like as illustrated in Fig. 4 comprises a generator I having a rotor 2 and a stator 3. The rotor is rotatably held on a foundation or supporting structure 4. In order to slow down the rotor and bring it to a quick standstill a plurality of jack and brake arrangements 5, 6 are provided, each arrangement being held on the supporting structure 4 and having an element cooperatively associated with a ring or like brake member 1 securely fastened to and forming part of the rotor 2. During normal operation of the rotor the jack and brake arrangements 5, 6 form a clearance 8 with the adjacent brake surface of the ring 1. Upon shutdown the jack and brake arrangements 5, `(i are raised frictionally to engage the ring 1. and upon standstill to support the rotor 2.

Each arrangement 5, 6 as shown inFigs. 1 to 3 comprises a hydraulic cylinder IU with a bottom I I fused to a base I2 by a weld I3. A conduit I4 projects through an opening in the base I2 and is secured to a channel I5 in the cylinder wall for rconducting fluid `under pressure, such as air vor oil, tothe cylinder. A plunger or piston I6 is slidably disposed within the cylindrical chamber formed by the cylinder I0. The piston I has a central bore I1 and the lower end of the piston forms a central cylindrical vextension or projection I8. The upper end of the bore I1 is sealed by means of a plug I9. A stud 20 screwed into an opening of the bottom II projects centrally into thebore I1 and at its upper end carries a nut 2I forming a seat for the upper kend of a helical spring 22 surrounding the stub A2l) and having a lower end bearing against a shoulder 23 formed at the lower end of the extension I8. The spring 22 is under compression and biases the plunger I6 into its lower end position in which it engages the bottom II of the cylinder (Fig. 1). Packing means are provided toreduce leakage of operating medium along the clearance between the plunger and the wall. of the cylinder. This packing means includes a sealing ring 24 having 'a cylindrical portion engaging the wall of the cylinder IG and biased radially outward towards the wall by means of a spring 25 held in a retainer 26, which latter together with a disk portion of the ring 24 is secured to the lower face of the plunger I6 by a plurality of `bolts 21. The upper end of the plunger I 6 in `the present example is secured to a platformy or friction block plate 28 by a plurality of bolts 29. The platform 28 carries a shoe in the form of a dat friction block or disk 30 made of suitable brake material. The platform and shoe are cooperatively associated with an object ,such as a brake ring 1 to be raised or to be engaged by the block '30 to reduce rotary movement thereof.

During operation, fluid under pressure is supplied to the conduit I4 through the lower end of the cylinder IIJ to effect upward movement of the piston I6. When the piston I6 has been raised to a desired position it may be held in such position by the provision of means mechanically locking or holding the piston and platform in position. This means according to my invention is in the form of two cylindrical cams 32 and 33 having adjacent like cam surfaces 34 and 35 respectively and concentrically surrounding the cylinder IU. The lower cam 32 is loosely held on the base I2 and rotatable about the cylinder I0 whereas the upper cam 33 is secured to the platform 28 by a weld 36. The upper cam 33 has an axial slot 31. A guide pin 38 secured to the cylinder IIJ projects through the slot 31 and prevents rotational movement of the plunger and the cam 33, 'which latter is secured to the plunger through the intermediary of the platform. The lower cam 32 has a radial projection or attachment 39 with a bore or opening 40 for receiving a rod or like tool to turn the lower cam about the axis of the cylinder in order to bring the cam surface 34 of the lower cam into engagement with the cam surface 35 of the upper cam.

Fig. 2 shows the arrangement in raised position, the cam surfaces 34, 35 being axially spaced. After' the plunger l5 with the platform 28 has thus been raised the lower rotatable cam 32 may be turned or rotated until the cam surfaces 34, 35 engage each other again. The arrangement is shown in such position in Fig. 3. Thereupon the hydraulic fluid under pressure in the cylinder chamber may be relieved. The platform then is being held in elevated position by the cams 34, 35 which together constitute a means for supporting the platform 28 in any raised position. The carn surfaces 34, 35 have a small pitch. Therefore, with the platform or the shoe 30 supporting a heavy object, such as part of a large hydro-electric generator, the jack could not be lowered mechanically by merely turning the lower cam. In order to lower the jack it is neces sary first to admit fluid under pressure to the cylinder chamber in order to raise slightly the upper cam from the lower cam. Thereupon the lower cam may be moved from the position in Fig. 3 into that of Fig. 2 so that upon release of the fluid pressure the piston I6 may move downward into engagement with the bottom l l. This downward movement is partly effected by the biasing action of the spring 22.

Thus, with my invention I have accomplished an improved construction of hydraulic jack arrangements used in combination with vertically disposed electric generators to bring the rotors thereof to a quick standstill upon shutdown and to hold the rotors in vertically raised position upon release of the fiuid pressure from the jacks. Upon restarting of the rotor it is desirable first to apply fluid pressure to the thrust bearings before the jacks are lowered to permit rotation of the rotor. The jack arrangements reduce considerably the wear of the thrust bearings because they facilitate the formation of a lubricating film on the thrust bearings while the rotor is standing still.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Hydraulic jack arrangement comprising a hydraulic cylinder having a connection for receiving fluid under pressure, a plunger slidably disposed in the cylinder, and means for holding anv object hydraulically raised to a certain position by the plunger comprising cylinder cam means concentrically surrounding the cylinder.

2. Hydraulic jack arrangement comprising a hydraulic cylinder having an opening for receiving fluid under pressure, a plunger slidably disposed in the cylinder, a platform facing an open end of the cylinder and fastened to the plunger, and cylindrical cam means surrounding the cylinder for locking the platform in any raised position.

3. Hydraulic jack arrangement comprising a hydraulic cylinder having an opening for receiving fluid under pressure, a plunger slidably disposed in the cylinder, a platform fastened to the plunger, and means for holding the platform in any raised position, said means including a lower cam rotatable about the cylinder and an upper cam secured to the platform, adjacent ends of the cams forming helical cam surfaces.

4. Hydraulic jack arrangement comprising a hydraulic cylinder having an opening for receiving fluid under pressure, a plunger slidably disposed in the cylinder, a platform fastened to the plunger, and cylindrical cam means surrounding the cylinder for holding the platform in any raised position upon release of the fluid pressure, said cam means including a cam with an axial slot surrounding the cylinder and being secured to the platform and a guide pin secured to the cylinder and projecting through the slot to prevent rotational movement of the plunger and said cam.

WALTER E. MAINWARING. 

